1. Field of the Invention
The present invention relates to a cylinder injection type fuel injection valve which is attached to a cylinder head for directly injecting fuel into a combustion chamber of a combustion engine.
2. Discussion of Background
FIG. 3 is a side cross-sectional view showing a conventional fuel injection valve, wherein the fuel injection valve generally has a structure of combining a fuel injection valve body having a needle valve and a solenoid for operating the needle valve. In the Figure, a reference numeral 21 designates a core; a reference numeral 22 designates a housing; a reference numeral 23 designates an O-ring for sealing fuel; a reference numeral 24 designates a coil assembly; and a reference numeral 25 designates an air gap. The core 21 and the housing 22 are caulked at a connecting portion therebetween in order to obtain a withstand pressure strength. Further, in the Figure, a reference A designates a caulked portion; a reference numeral 26 designates a valve device; and a reference numeral 27 designates a needle valve of the valve device.
The conventional fuel injection valve is constructed as described above. Therefore, there was a problem that the caulked portion between the core and the housing would loosen under a high combustion pressure; an air gap was changed by an upward movement of the core; and an injection amount was changed by a change of valve suction force, when the conventional structure of fuel injector was used for injecting fuel into cylinder.
Further, there was a return of a caulked portion in a housing when a method of caulking was solely used. Therefore, there was a possibility that an air gap was changed by looseness of the caulked portion.
Further, it is necessary to increase a caulking load in order to increase a strength of caulking. However, there was a problem such that the housing was buckled when the caulking load was increased.